DEFINITION OF A RANGE OF IDEALIZED VALUES TO CHARACTERIZE SEATED BODYBIODYNAMIC RESPONSE UNDER VERTICAL VIBRATION

While a considerable quantity of data has been published on driving-po int mechanical impedance, apparent mass and seat-to-head transmissibil ity magnitude and phase characteristics of seated subjects under verti cal whole-body vibration, significant variation is known to exist betw een various data sets. Such variations may be partly attributed to dif ferences associated with the methodology, experimental conditions or s ubject population used by various investigators to determine the biody namic response characteristcs. As part of this study, various publishe d data sets on driving-point mechanical impedance, apparent mass and s eat-to-head transmissibility are identified for which the experimental conditions are reported to fall within a prescribed range of conditio ns for subjects maintaining an erect seated posture without backrest s upport, while the feet are supported on a vibrating platform. Only tho se data sets are considered for which the magnitude of vertical sine a nd/or random excitation is reported to have been maintained below 5m s (-2). A further screening of the data sets defining the magnitude and phase responses of each function is performed by eliminating all data representing outliers in the 0.5-20 Hz frequency range. On that basis, mean and envelopes of the magnitude and phase responses associated wi th each function are derived in the 0.5-20 Hz frequency range, represe nting the most probable values likely applicable under the predefined range of conditions. The resulting range of idealized values on the ma gnitude and phase responses are based on 8 and 7 data sets respectivel y for driving-point mechanical impedance and apparent mass, while only 4 and 3 data sets respectively were left to define the seat-to-head t ransmissibility magnitude and phase. (C) 1998 Academic Press.